The crossing of the Alps: The Bleriot XI

Let us look at the Bleriot XI plane that Jorge Chavez bought, its characteristics and the modifications made by him.

The Bleriot XI plane was a monoplane, single seat with a single engine, with a gradually tapering fuselage formed by ash longerons, and only half covered by fabric. The fuselage had cables made from 1, 5 mm. piano strings. The wings and the vertical tail plane were also made of wood, covered with fabric. It had two bronze barrel-like fuel tanks, which were installed on the front part of the fuselage, over the pilot’s legs.

The landing gear consisted of two large bicycle-type wheels, with shock absorbers, and it had an additional wheel on the back and lower part of the fuselage, which acted as a tail pedal. Jorge Chavez had this wheel removed and instead, instructed the manufacturers to place two “U” curved intertwined tackles , which were fixed to the back and lower part of the fuselage, in front of the tail planes.

This device designed by Jorge Chavez permitted him to make shorter landings and to land in slopes acting as a brake. It allowed him to reduce the speed when the plane entered in contact with the land, for at that time the front wheels did not have braking systems.

In the front part of the plane, in front of the pilot’s cockpit, the Bleriot XI was provided with a castle- type structure, with two triangular bases attached to the upper vertices by a bar, from which tensor cables were attached to the wings. In the lower part of the fuselage, under the pilot’s seat, there was another small castle-like structure, with tensor cables that fixed the wings to the lower part of the plane. The tensor cables of both castle-like structures consisted on two 2 to 2, 5 mm piano strings, and the ones in the front part were 3 mm piano strings. The throttle, when moved, generated tension in the cables towards the wings and produced the necessary torsion to make both left and right turnings, because the airplane did not have flaps. This throttle, when moved backwards or forward, moved the 2, 5 mm cables which in turn, moved the rudder on the plain tail, whether to climb or to descend. The pedals moved the rudder on the tail plane.

The propeller engine of the Bleriot XI was a 7 – cylinder rotary Gnome Omega delivering 50 HP, lubricated with castor oil and which tank was next to it. The cooling of the engine was achieved through impact air. This engine activated a two blade propeller, which produced traction, rotating at a rate o 200 to 1 250 revolutions, which were registered in the tachometer. In order to reduce the possibility of ice formation in altitude flights, the engine oil conducts were covered with wrappings made up of asbestos and wool, designed by Jorge Chavez.

In order to record the flight altitude, taking into consideration that the altimeter had not been invented yet, the pilots used a portable barometer. This was a small, light aluminum box with a glass lid, which contained a clockwork system inside that acted on a cylinder where a small millimeter paper rolled up; this paper came from a parallel coil. An aneroid articulated the mechanism made up by a sensitive and delicate pointer which had a feather with a small reservoir for special ink attached to it. As the paper rolled, this feather graphically registered the variations of the millibar pressure, indicating the climb or descent conditions, which allowed to finally decipher the altitude at which the plane was flying.

The plane was also equipped with a compass and a tachometer. It did not have any other altitude control instruments. The pilot was only able to control the plane through visual contact, and the navigation was performed by estimation.

The cockpit did not provide any protection for the pilot, and it had no windscreen. This forced the pilot to use flying glasses and adequate warm clothes, for during the flight the cold wind would hit the pilot directly on the face, breast and head. Jorge Chavez had had a special flight anorak tailor made for him. I was lined in china paper and covered with impermeable silk on the outside; it had large amounts of asbestos between linings, which provided him good protection against the cold weather. Inside the cockpit there was only a light wooden and wicker seat, without any belts or straps to keep the pilot buckled during the flight. There was also a control stick, fitted with a small steering wheel on the upper part. The engine accelerator control was inside the cockpit, and the compass was fixed on the side, making up a central panel. The tachometer which Chavez had installed in the Bleriot was fixed in the upper left side of the cockpit, and the map loom, in the upper central part, next to the compass. The barometer box hung from the pilot’s neck with straps. The barometer was a piece of equipment used by geographers, which Chavez had adapted to take with him during his flights.

The dimensions, weight and characteristics of the Bleriot XI plane were the following:

Wingspan 7.20 m

Cord 2.05 m

Length 8 m

Height 2.55 m

Lift area 14 square meters

Empty weight 158 kg.

Weight of the 50 HP Gnome engine: 110 kg.

Load 144 kg

Total weight: 412 kg.

Minimum speed 50/55 km/h

Maximum speed 90 km/h.

Propeller revolutions from 200 to 1,250

Maximum Altitud: 4,000 m.

As you can see, the airplanes were this rudimentary and simple, - as the Bleriot XI– in the early XXth Century, very different to the ones that appeared at the end of the XX Century and early XXI, almost one hundred years later, and which we have known and had the opportunity to fly or watch fly. How fragile and poorly equipped were these flying machines in which the aviators flew and in which airman Jorge Chavez ventured, with decision and courage, to be the first one to cross the Alps!. What a great courage the young Peruvian had to defeat a great natural barrier and to open a new air route between Switzerland and Italy, giving his live for the progress of world aviation!.

Now that we know the characteristics of the plane purchased by Jorge Chavez, we will move on to explain how he achieved the altitude record on September 8, 1910, when he had just received the Bleriot XI plane with the modifications he had asked for.